To meet the demand for higher integration density and operating speed of LSIs, the effort to reduce the pattern rule is in rapid progress. The wide-spreading flash memory market and the demand for increased storage capacities drive forward the miniaturization technology. As the advanced miniaturization technology, manufacturing of microelectronic devices at the 65-nm node by the ArF lithography has been implemented in a mass scale. Manufacturing of 45-nm node devices by the next generation ArF immersion lithography is approaching to the verge of high-volume application. The candidates for the next generation 32-nm node include ultra-high NA lens immersion lithography using a liquid having a higher refractive index than water in combination with a high refractive index lens and a high refractive index resist film, extreme ultraviolet (EUV) lithography of 13.5 nm wavelength, and double patterning version of the ArF lithography, on which active research efforts have been made.
With the advance of miniaturization, it is confirmed that line width roughness (LWR) has an impact on the performance of transistors. A reduction of LWR is thus demanded. Effective approaches for reducing LWR include an increase in the amount of PAG added, addition of an acid generator capable of generating an acid which does not cause deprotection of a protective group, and binding of PAG to a polymer backbone. Highly transparent PAGs which do not detract from transparency even when added in larger amounts, acid generators capable of generating weak acids, and PAG-bound polymers have been developed.
Efforts to develop molecular resist materials were made under the hypothesis that a monomer is more effective for reducing LWR due to the smallness of its molecular size than a polymer. Such molecular resist materials include acid labile group-substituted phenolic low nuclear compounds, calix-resorcin, NORIA, truxene, cyclodextrin and other phenol derivatives. JP-A H08-15865 discloses a molecular resist material comprising acid labile group-substituted cholate. As compared with polymeric resist materials, molecular resist materials allow for extensive and non-uniform acid diffusion. For this reason, molecular resist materials fail to achieve a LWR level surpassing polymeric resist materials. It would be desirable to have a molecular resist material which is effective for suppressing acid diffusion to achieve a lower LWR than polymeric resist materials.